4.7 understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer

Food Chains:

- Show what's eaten by what.

- Food chains always start with a producer. In this case, the flower is the producer as it produces its own food using the sun's energy via photosynthesis. (photosynthesis produces glucose!)

- Producers are eaten by primary consumers, which are then eaten by secondary consumers, and secondary consumers are then eaten by tertiary consumers. 

- All these organisms die eventually and get eaten by decomposers like bacteria. 

*Each stage (e.g. producers, primary consumers...) is called a trophic level.

Food Webs:

- Shows how food chains are linked to more complex feeding relationships. 

- There are many different species in the environment. Therefore food webs can be used to show these species.

- All species in the food web are interdependent. This means that if one species changes, it affects all others. 

- e.g. if lots of water spiders died, then there would be less food for frogs, causing their numbers to decrease. The number of mayfly larvae can therefore increase, and diving beetles would have less competition therefore the number of diving beetles would increase.

Pyramids of Numbers: 

-Wider bar indicates a larger population.

- As energy is lost to surroundings from one trophic level to the next, there are usually fewer organisms with each tropic level due to decreased chances of survival.

Pyramids of Biomass:

- Shows the total mass of organisms in each trophic level. 

- Each bar represents the mass of living materials all organisms at each trophic level would "weigh" if you put them all together. 

- In this case, one fox would have big biomass and the hundreds of fleas would have very small biomass. Biomass pyramids are almost always in the right pyramid shape.

Pyramids of Energy Transfer:

- Always pyramid-shaped as energy is lost to the surroundings and only 10% of energy is passed from one trophic level to the next.